This invention relates to a wiper system for an exterior rear view mirror used on motor vehicles and is particularly adapted for such mirrors used on trucks and buses. Various types of wiper systems have been proposed or used, for example, wiper systems with laterally or horizontally moving wiper blades are disclosed in U.S. Pat. Nos. 3,855,661 and 4,763,381, and wiper systems with vertically moving wiper blades are disclosed in U.S. Pat. Nos. 4,873,740, 5,157,511 and 5,522,112. With any such wiper system, it is desirable for the wiper blade to clean or wipe substantially the entire front surface of the rear view mirror and to be constructed so that the wiper system would not be damaged in the event the wiper blade becomes frozen to the mirror. It is also desirable for the wiper system to be dependable in operation regardless of weather conditions and for the wiper blade to be normally stored in a position where it does not interfere with normal use of the mirror. It is also important for the wiper blade to wipe and clean the mirror surface during each stroke of the blade without water following the blade.
The present invention is directed to an improved wiper system which provides all of the desirable features mentioned above and which is constructed either as an integral part of the vehicle mirror unit or as a separate attachment for the mirror unit. In accordance with one embodiment of the invention, the wiper system is partially enclosed within a non-magnetic stainless steel housing which supports a vertical rectangular mirror. A formed non-magnetic stainless steel track is attached to the housing and supports a carriage for vertical movement adjacent one side of the mirror. The carriage pivotally supports one end portion of a horizontal wiper arm, and a wiper blade unit is pivotally supported by the opposite end portion of the arm. A torsion spring biases the arm and wiper blade towards the surface of the mirror.
A vertical drive or lead screw with reversing helical grooves is supported within the housing and is rotated by a DC permanent magnet motor through a belt drive. A shuttle is mounted on the lead screw for vertical reciprocating movement, and the shuttle and the carriage support an opposing set of magnets with the track and housing extending between the opposing magnets. The carriage, wiper arm and wiper blade are thus moved up and down the track with the wiper blade contacting the mirror in response to vertical reciprocating movement of the shuttle and through a magnetic coupling.
A cam member is mounted on the upper portion of the housing and is engaged by a cam lift finger pivotally connected to the wiper arm. As the wiper blade moves upwardly to the upper end of its stroke, the cam member lifts the wiper blade from the mirror and resets the blade back onto the mirror after the blade moves up slightly. This assures that the water carried by the wiper blade on the upstroke is then carried by the wiper blade on the downstroke. In a second embodiment, the wiper system of the invention is constructed for attachment to an existing rear view mirror mounted on a motor vehicle. In this embodiment, the housing surrounding the lead screw and shuttle may be formed from a non-metallic stainless or aluminum or a plastics material.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.